JP2011196396A - Structure for preventing press-fitting part from coming off - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure for preventing a press-fitting part from coming off, capable of achieving a miniaturized and lightweight product which includes the press-fitting part press-fitted around an outer periphery of a hollow shaft.SOLUTION: The structure for preventing a counter gear 40 press-fitted around an outer periphery of a drive pinion 20 from coming off includes: a bearing 32 which is press-fitted around the outer periphery of the drive pinion 20 and abuts to the counter gear 40 to prevent the counter gear 40 from coming off from the drive pinion 20; and a columnar part 50 which is press-fitted around an inner periphery of the drive pinion 20 and distorts a press-fitted portion of the bearing 32 of the drive pinion 20.

Description

  The present invention relates to a retaining structure for press-fitting parts press-fitted into the outer periphery of a hollow shaft. In particular, it is suitable for use in a speed reduction mechanism in a vehicle drive device.

  For example, there is a speed reducer in a vehicle drive device as a part in which components are press-fitted into the outer periphery of the hollow shaft. As shown in FIG. 3, the reduction gear 100 is configured as a gear subassembly in which a counter gear 140 corresponding to a press-fitting part is press-fitted into a drive pinion 120 corresponding to a hollow shaft and integrated. Both ends of the drive pinion 120 are supported by bearings 131 and 132 so that the drive pinion 120 and the counter gear 140 rotate together.

  Here, the counter gear 140 is formed as a helical gear in order to reduce gear noise. Therefore, when the counter gear 140 is engaged with the counter gear 140 in the direction away from the drive pinion 120 (rightward in FIG. 3) with respect to the counter gear 140 either during forward rotation (when the vehicle moves forward) or when the vehicle rotates backward (when the vehicle moves backward). The generated thrust force (hereinafter referred to as “disengagement force”) Fa acts. For this reason, in order to function as a gear sub-assembly, it is necessary to prevent the counter gear 140 from coming out of the drive pinion 120 against the removal force Fa. For this reason, the lock nut 150 is arranged via the bearing 132 coaxially in series with the gear sub-assembly, and the axial force of the lock nut 150 is generated as a retaining force to prevent the counter gear 140 from coming off from the drive pinion 120. (See Patent Document 1).

JP 2004-68850 A

  However, the conventional structure using the lock nut described above has a problem that the shaft length and the mass of the gear subassembly increase. That is, the size and mass of the product (integrated rotating shaft) including the press-fitted parts press-fitted into the outer periphery of the hollow shaft are increased, and it is difficult to reduce the size and weight of the product.

  Therefore, the present invention has been made to solve the above-described problems, and has a press-fit component retaining structure capable of reducing the size and weight of a product including a press-fit component press-fitted into the outer periphery of a hollow shaft. The purpose is to provide.

  One aspect of the present invention made to solve the above-described problems is that in a retaining structure for a press-fitted component press-fitted into the outer periphery of a hollow shaft, the press-fitted component is press-fitted into the outer periphery of the hollow shaft and abutted against the press-fitted component. A first component that prevents the component from coming off from the hollow member; and a second component that is press-fitted into the inner periphery of the hollow shaft and that distorts the press-fitted portion of the first component in the hollow shaft. It is characterized by.

  In this retaining structure, the press-fitting portion of the first part in the hollow shaft can be distorted by the second part press-fitted into the inner periphery of the hollow shaft, and the press-fitting allowance of the first part can be increased. . Thereby, it is possible to increase the retaining force in the second component (the resistance against the pulling force acting on the press-fitted component, that is, the frictional force between the second component and the hollow shaft). As a result, the second part can prevent the press-fit portion from coming off from the hollow shaft without using a lock nut. Thus, since it is not necessary to use a lock nut, the retaining structure is simplified, and the product can be reduced in size and weight.

  In the press-fitting component retaining structure described above, it is desirable that the second component is disposed so as to overlap the first component in the axial direction.

  By doing in this way, since the axial length of a hollow shaft does not increase or is shortened, the product can be further reduced in size and weight.

  In the press-fitting component retaining structure described above, the first component is a bearing that supports the hollow shaft, and the second component is a hollow or solid cylindrical member. Good.

  By doing so, it is possible to realize a press-fitting component retaining structure capable of reducing the size and weight of the product with a very simple configuration. In particular, when the second part is a hollow product, it is more advantageous in reducing the weight of the product, and the oil supply to the bearing is also simplified, so that a simpler configuration can be achieved.

  In the press-fitting component retaining structure described above, it is preferable that the second component has a flange that contacts the first component at one end.

  By doing in this way, since the collar part of a 2nd part suppresses a press-fit part, the axial force which generate | occur | produces by the press-fit of a 2nd part can also be utilized as a retaining force. Accordingly, since the retaining force can be further increased, the second component can be thinned, and the product can be further reduced in size and weight.

  In the press-fitting component retaining structure described above, it is desirable that the second component is formed of a metal having a higher longitudinal elastic modulus than the hollow shaft. For example, the second component may be formed of a beryllium alloy or a tungsten alloy.

  By doing so, the rigidity of the second part can be increased, and when the hollow part is press-fitted, a larger strain can be applied to the press-fitted portion of the first part in the hollow shaft. . As a result, it is possible to reduce the thickness of the second component as much as the retaining force can be increased, and the product can be further reduced in size and weight.

  In the press-fitting component retaining structure described above, the second component is preferably press-fitted into the inner periphery of the hollow shaft after the first component is press-fitted into the outer periphery of the hollow shaft.

  With such a configuration, the press-fit load of the first part and the press-fit load of the second part do not increase. That is, the first component is press-fitted into the hollow shaft even in the conventional structure using a lock nut, and the first component and the second component can be press-fitted into the hollow shaft with a load smaller than the press-fitting load. it can. Therefore, since the first part and the second part can be press-fitted into the hollow shaft using conventional equipment, there is no need to provide new equipment.

  According to the press-fitting component retaining structure according to the present invention, as described above, it is possible to reduce the size and weight of a product including the press-fitting component press-fitted into the outer periphery of the hollow shaft.

It is sectional drawing which shows schematic structure of the speed reducer which concerns on 1st Embodiment. It is sectional drawing which shows schematic structure of the speed reducer which concerns on 2nd Embodiment. It is sectional drawing which shows schematic structure of the conventional speed reducer.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying a press-fitting component retaining structure according to the present invention will be described below in detail with reference to the drawings. In the present embodiment, a case where the present invention is applied to a reduction gear provided in a vehicle drive device is illustrated.

[First Embodiment]
First, the first embodiment will be described. Therefore, the speed reducer according to the present embodiment will be described with reference to FIG. FIG. 1 is a cross-sectional view showing a schematic configuration of the speed reducer according to the first embodiment.

  As shown in FIG. 1, the speed reducer 10 includes a drive pinion 20, bearings 31 and 32, a counter gear 40, and a cylindrical part 50, and is configured as a gear subassembly. The drive pinion 20 is a hollow shaft, and a drive pinion gear 21 is formed in part. The drive pinion gear 21 meshes with a ring gear of a differential device (not shown). The drive pinion 20 is rotatably supported by bearings 31 and 32 at both ends. Further, the drive pinion 20 is restrained and supported in the axial direction by the bearings 31 and 32, and movement in the axial direction is restricted. The bearings 31 and 32 are press-fitted into the drive pinion 20.

  On the outer periphery of the drive pinion 20, a counter gear 40 is spline fitted and press-fitted and attached. The counter gear 40 rotates together with the drive pinion 20. The counter gear 40 is formed as a helical gear for gear noise reduction or the like, and meshes with a counter driven gear formed on an input shaft connected to a driving source (not shown) (engine, motor, etc.). Thereby, in the reduction gear 10, the rotation of the input shaft is decelerated via the counter gear 40, the drive pinion 20 and the drive pinion gear 21 and transmitted to the differential device.

  The cylindrical part 50 is press-fitted into the inner periphery of the end of the drive pinion 20. More specifically, the cylindrical part 50 is disposed on the end of the drive pinion 20 on the side where the bearing 32 is disposed so as to overlap the bearing 32 in the axial direction. Thus, when the cylindrical part 50 is press-fitted into the drive pinion 20, the fitting surface 20a of the drive pinion 20 with the bearing 32 is distorted to the outer peripheral side. The bearing 32 is firmly attached to the drive pinion 20 by the distortion of the fitting surface 20a. The cylindrical member 50 is formed of a metal (for example, beryllium alloy or tungsten alloy) having a higher longitudinal elastic modulus than the drive pinion 20 and is press-fitted in a state where the bearing 32 is press-fitted into the drive pinion 20. Yes.

  Here, since the counter gear 40 is a helical gear, the release force Fa is applied to the counter gear 40 in the direction of releasing from the drive pinion 20 either during forward rotation (when the vehicle moves forward) or during reverse rotation (when the vehicle moves backward). Works. Therefore, it is necessary to prevent the counter gear 40 from coming out of the drive pinion 20 against the withdrawal force Fa. Therefore, in the present embodiment, the counter gear 40 is prevented from coming off by the bearing 32 and the cylindrical part 50.

  That is, since the cylindrical part 50 is press-fitted into the inner periphery of the drive pinion 20 to give a positive distortion to the fitting surface 20a, the press-fitting allowance of the bearing 32 increases, so that the surface pressure at the fitting surface 20a increases. In addition, the frictional force between the bearing 32 and the drive pinion 20 increases. For this reason, as a result of the axial force (increased frictional force) due to the press-fitting of the cylindrical part 50 being applied to the retaining force Fb of the bearing 32, the retaining force Fb increases.

そして、締付力Ｐは、軸受３２をドライブピニオン２０に圧入することで発生する締付力Ｐ₁ と、円柱状部材５０をドライブピニオン２０に圧入することで発生する締付力Ｐ₂ により、数２で表すことができる。

Here, the retaining force Fb of the bearing 32 can be expressed by Equation 1 by the radial tightening force P and the friction coefficient μ with respect to the fitting surface 20a.

The tightening force P is determined by the tightening force P ₁ generated by press-fitting the bearing 32 into the drive pinion 20 and the tightening force P ₂ generated by press-fitting the columnar member 50 into the drive pinion 20. This can be expressed by Equation 2.

Therefore, the retaining force Fb of the bearing 32 is increased by the frictional force μP ₂ generated by the tightening force P ₂ generated by the press-fitting of the cylindrical part 50. As a result, even if the bearing 32 is not fastened with a lock nut as in the prior art, the counter gear 40 can be reliably prevented from being detached from the drive pinion 20 by the bearing 32 and the cylindrical part 50. Thus, since the speed reducer 10 does not use a lock nut, the retaining structure can be simplified. As a result, the reduction gear 10 can be reduced in size (mainly axial dimension reduction) and reduced in weight. Further, since the cylindrical part 50 is arranged so as to overlap the counter gear 40, the drive pinion 20 can be made shorter than the conventional one, and the reduction gear 10 can be further reduced in size and weight. Can do.

なお、数３及び数４における各記号は、
Ｓ₁：嵌め合い面２０ａにおける軸受３２とドライブピニオン２０との接触面積
Ｓ₂：嵌め合い面２０ｂにおける円柱状部品５０とドライブピニオン２０との接触面積
ｐ₁：嵌め合い面２０ａでの締付圧力
ｐ₂：嵌め合い面２０ｂでの締付圧力
ｄ ：軸受３２の内輪の内径（≒嵌め合い面２０ａにおけるドライブピニオン２０の外径）
ｄ₀：ドライブピニオン２０の内径（≒嵌め合い面２０ｂにおける円柱状部品５０の外径）
Ｂ ：軸受３２の圧入長さ
を示している。 Here, the tightening forces P ₁ and P ₂ can be expressed by Equation 3 and Equation 4, respectively.

Each symbol in Equation 3 and Equation 4 is
S ₁ : Contact area between the bearing 32 and the drive pinion 20 on the mating surface 20 a S ₂ : Contact area between the cylindrical part 50 and the drive pinion 20 on the mating surface 20 b p ₁ : Tightening pressure on the mating surface 20 a p ₂ : Tightening pressure at the mating surface 20 b d: Inner diameter of the inner ring of the bearing 32 (≈outer diameter of the drive pinion 20 at the mating surface 20 a)
d ₀ : Inner diameter of the drive pinion 20 (≈outer diameter of the cylindrical part 50 on the mating surface 20b)
B: The press-fit length of the bearing 32 is shown.

なお、数５及び数６における各記号は、
δ₁：軸受３２の圧入締め代
δ₂：円柱状部品５０の圧入締め代
Ｅ₁：ドライブピニオン２０の縦弾性係数
Ｅ₂：軸受３２の縦弾性係数
Ｅ₃：円柱状部品５０の縦弾性係数
ν₁：ドライブピニオン２０のポアソン比
ν₂：軸受３２のポアソン比
ν₃：円柱状部品５０のポアソン比
ｄ₁：円柱状部品５０の内径
を示している。 Then, the tightening pressures p ₁ and p ₂ can be obtained by Equations 5 and 6, respectively.

Each symbol in Equations 5 and 6 is
δ ₁ : press-fit tightening allowance of bearing 32 δ ₂ : press-fit tightening allowance of cylindrical part 50 E ₁ : longitudinal elastic modulus of drive pinion 20 E ₂ : longitudinal elastic coefficient of bearing 32 E ₃ : longitudinal elastic coefficient of cylindrical part 50 ν ₁ : Poisson's ratio of the drive pinion 20 ν ₂ : Poisson's ratio of the bearing 32 ν ₃ : Poisson's ratio of the cylindrical part 50 d ₁ : The inner diameter of the cylindrical part 50 is shown.

Here, in order to increase the tightening pressure p ₂ in order to increase the retaining force Fb, it can be seen from Equation 6 that the inner diameter d ₀ of the drive pinion 20 may be decreased. However, if the inner diameter d ₀ of the drive pinion 20 is reduced, the mass of the drive pinion 20 increases, so that it is difficult to reduce the weight of the reduction gear 10. Therefore, it is also conceivable to make the drive pinion 20 solid only in the portion where the bearing 32 is press-fitted without using the cylindrical part 50, or to increase the thickness of the drive pinion 20. However, if the drive pinion 20 has such a shape, thermal distortion during heat treatment does not occur uniformly in the axial direction of the drive pinion 20, so that the product accuracy of the drive pinion 20 may not be ensured. Further, since a large step is formed on the inner periphery of the drive pinion 20, there is a possibility that the oil flow in the drive pinion 20 may be hindered depending on use conditions. And if the oil flow in the drive pinion 20 is obstructed, the performance and durability of the reduction gear 10 will be reduced.

Therefore, in the reduction gear device 10 according to the present embodiment, the inner diameter d ₀ of the drive pinion 20 is increased in order to avoid a decrease in performance and durability due to an increase in the mass of the drive pinion 20 and an obstruction of the oil flow. . Therefore, the retaining force Fb may be reduced. However, the reduction gear 10, since the inner circumferential giving strain to the surface 20a fitting by press-fitting the cylindrical part 50 to generate a clamping force P ₂ to the drive pinion 20, the retaining force Fb is reduced It can be increased without any problems.

Thereby, in the speed reducer 10, the inner diameter d ₀ of the drive pinion 20 is within the range where the retaining force Fb is larger than the retaining force Fa (Fb> Fa) without being affected by requirements such as heat treatment and oil flow. Therefore, it is possible to reduce the weight while preventing the counter gear 40 from coming off. Further, as compared with the conventional reduction gear, only the hollow cylindrical part 50 is provided instead of the lock nut, so that the retaining structure is very simple and the weight can be reduced.

Further, the cylindrical member 50 for longitudinal elastic coefficient than the drive pinion 20 is formed with high metal, for fastening the pressure p ₂ increases, increases clamping force P _2. Therefore, as a result of the tightening force P being increased, the retaining force Fb is also increased. Thus, as the retaining force Fb increases, the cylindrical part 50 can be thinned, and the reduction gear 10 can be further reduced in size and weight.

  Further, in the reduction gear device 10, the cylindrical part 50 is press-fitted into the inner periphery of the drive pinion 20 after the bearing 32 is press-fitted into the outer periphery of the drive pinion 20. Each press-fit load does not increase. That is, the bearing is press-fitted into the drive pinion even in a conventional structure using a lock nut, and the bearing 32 and the cylindrical part 50 can be press-fitted into the drive pinion 20 with a load smaller than the press-fitting load at this time. Therefore, since the bearing 32 and the cylindrical part 50 can be press-fitted into the drive pinion 20 using conventional equipment, it is not necessary to provide new equipment.

As described above in detail, according to the reduction gear device 10 according to the present embodiment, the cylindrical part 50 is press-fitted into the inner periphery of the drive pinion 20, and the fitting surface 20 a is distorted to be fastened to the bearing 32. A force P ₂ is generated to increase the retaining force Fb of the bearing 32. As a result, the counter gear 40 can be prevented from coming off without using a lock nut. As a result, the retaining structure can be simplified, and the reduction gear 10 can be reduced in size and weight.

[Second Embodiment]
Next, a second embodiment will be described. The basic configuration of the second embodiment is substantially the same as that of the first embodiment, but the shape of the cylindrical member is slightly different. Therefore, in the following, the same components as those in the first embodiment will be denoted by the same reference numerals in the drawings, and the description thereof will be omitted as appropriate, and differences from the first embodiment will be mainly described. Therefore, a reduction gear according to the second embodiment will be described with reference to FIG. FIG. 2 is a cross-sectional view showing a schematic configuration of the reduction gear according to the second embodiment.

  As shown in FIG. 2, the speed reducer 10a also includes a drive pinion 20, bearings 31 and 32, a counter gear 40, and a cylindrical part 55, as in the first embodiment, and serves as a gear subassembly. It is configured. The cylindrical part 55 is made of a metal having a higher longitudinal elastic modulus than that of the drive pinion 20. The columnar part 55 is provided with a flange 55a. This cylindrical part 55 is also press-fitted into the drive pinion 20 after the bearing 32.

  The flange portion 55a is formed at one end portion (right end portion in FIG. 2) of the columnar member 55 so as to extend to the outer periphery. The flange 55a is in contact with the end of the inner ring 32a of the bearing 32 (the end opposite to the end in contact with the counter gear 40). That is, the columnar member 55 presses the bearing 32 against the counter gear 40 via the flange 55a. Thereby, the axial force generated by the press-fitting of the cylindrical member 55 can also be used as the retaining force Fb. Accordingly, since the retaining force Fb can be further increased, the cylindrical part 55 can be thinned, and the reduction gear 10a can be further reduced in size and weight.

  Thus, according to the reduction gear device 10a according to the second embodiment, the retaining force Fb is increased by using the cylindrical part 55 formed with the flange portion 55a as compared with the first embodiment. be able to. As a result, the cylindrical part 55 can be thinned by an increase in the retaining force Fb, and the reduction gear 10a can be reduced in size and weight.

  It should be noted that the above-described embodiment is merely an example and does not limit the present invention in any way, and various improvements and modifications can be made without departing from the scope of the invention. For example, in the above-described embodiment, the cylindrical parts 50 and 55 are made of a metal having a higher longitudinal elastic modulus than that of the drive pinion 20, but can be made of the same metal (general steel) as the drive pinion 20. . Even in this case, the above-described effects can be obtained except for the weight reduction by thinning the cylindrical parts 50 and 55.

  In the above-described embodiment, the hollow member is used as the cylindrical parts 50 and 55, but a solid member can also be used. However, in this case, the oil passage for supplying oil to the bearing 32 becomes complicated, and the effect of reducing the weight is reduced.

  Further, in the above-described embodiment, the cylindrical parts 50 and 55 are press-fitted into the drive pinion 20 after the bearing 32, but the cylindrical parts 50 and 55 are inserted into the drive pinion 20 before the bearing 32. Can also be press-fitted. The effect mentioned above can be acquired also by this. However, in this case, since the press-fitting load of the bearing 32 is increased, new equipment may be required.

  In the embodiment described above, the present invention is applied to the speed reducer. However, the present invention is not limited to the speed reducer and is applied to a retaining structure for press-fitted parts press-fitted to the outer periphery of the hollow shaft. can do.

DESCRIPTION OF SYMBOLS 10 Deceleration device 20 Drive pinion 21 Drive pinion gear 31 Bearing 32 Bearing 40 Counter gear 50 Cylindrical component

Claims (6)

In the retaining structure of the press-fitted parts press-fitted into the outer periphery of the hollow shaft,
A first part that is press-fitted into the outer periphery of the hollow shaft and that is in contact with the press-fitted part and prevents the press-fitted part from coming off from the hollow member;
A press-fitting component retaining structure, comprising: a second component that is press-fitted into an inner periphery of the hollow shaft and distorts a press-fitted portion of the first component in the hollow shaft. In the press-fitting part retaining structure according to claim 1,
The press-fitting component retaining structure, wherein the second component is disposed so as to overlap the first component in the axial direction. In the retaining structure for press-fitting parts according to claim 1 or 2,
The first component is a bearing that supports the hollow shaft;
The second part is a member having a hollow or solid cylindrical shape, and a press-fitting part retaining structure. In any one press-fitting component retaining structure according to claim 1,
The press-fitting component retaining structure, wherein the second component is formed with a collar portion that contacts the first component at one end. In any one of the press-fitting parts retaining structures according to any one of claims 1 to 4,
The press-fitting component retaining structure, wherein the second component is made of a metal having a higher longitudinal elastic modulus than the hollow shaft. In any one press-fit component retaining structure according to any one of claims 1 to 5,
The press-fitting component retaining structure, wherein the second component is press-fitted into the inner periphery of the hollow shaft after the first component is press-fitted into the outer periphery of the hollow shaft.

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